1. Field of the Invention
Embodiments are in the field of bidirectional address conversion in SIP-controlled data streams between IPv4 and IPv6 data terminals.
2. Background of the Related Art
Telephone systems (Private Automatic Branch Exchange, or PABX) are transmission devices that connect multiple terminals such as telephone, fax, and answering machine to each other and also to the public telephone network. The basic operating element for performing this function is the so-called switching matrix, whose input and output channels are operated by a controller. Telephone systems provide a number of services, such as call forwarding, call transferring, call routing, and conference calls. In addition, certain rights are assigned to each individual terminal device within a telephone system, such as the right to make “outside calls” (for cost control).
Modern telephone systems perform these tasks using IP (Internet Protocol) technology, where the individual terminals are no longer connected to the telephone system with wiring, but rather are connected in a data network like PCs (personal computers). In IP networks, the user data (generally digitized voice data) are assembled in data packets and given a sender address and a target address, and the network infrastructure uses that target address to send the data packet to the terminal.
The IPv4 (Internet Protocol Version 4) normally used for this offers an address space for 232 (=4,294,976,296) possible addresses, which today is already almost used up. The further development of IPv4, called IPv6 and intended to resolve this limitation, offers a significantly larger address space for 2128 potential addresses. IPv6 is standardized in “Internet Protocol, Version 6 Specification; RFC2460 of the IETF (Internet Engineering Task Force). Connecting (partial) networks to the two different Internet protocols (IPv4 and IPv6) generates difficulties which in the SIP environment according to the current state of the art are resolved by the ICE (interactive connectivity establishment) protocol, for which it is necessary that all participating terminals operate according to the ICE protocol and that the user data be forwarded by a central server accessible to all participating terminals. The disadvantage with this is that the ICE protocol must be used in all participating terminals, which may require expensive changes to the control software of every device. EL MALKI, Karim [et al.]: “IPv6-IPv4 Translation mechanism for SIP-based services in Third Generation Partnership Project (3GPP) Networks. Network Working Group”, Internet Draft, December 2003, presents a method for bidirectional address conversion in SIP-controlled data streams between IPv6-enabled data terminals and IPv4-enabled data terminals.